[Mesa-dev] [PATCH 12/14] i965: Add fs_visitor::run_vs() to generate scalar vertex shader code

Kristian Høgsberg krh at bitplanet.net
Wed Oct 29 14:18:28 PDT 2014


On Tue, Oct 28, 2014 at 4:50 PM, Matt Turner <mattst88 at gmail.com> wrote:
> On Tue, Oct 28, 2014 at 3:17 PM, Kristian Høgsberg <krh at bitplanet.net> wrote:
>> This patch uses the previous refactoring to add a new run_vs() method
>> that generates vertex shader code using the scalar visitor and
>> optimizer.
>>
>> Signed-off-by: Kristian Høgsberg <krh at bitplanet.net>
>> ---
>>  src/mesa/drivers/dri/i965/brw_fs.cpp         | 101 ++++++++-
>>  src/mesa/drivers/dri/i965/brw_fs.h           |  21 +-
>>  src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 312 ++++++++++++++++++++++++++-
>>  3 files changed, 423 insertions(+), 11 deletions(-)
>>
>> diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
>> index dfad6b9..93f6a49 100644
>> --- a/src/mesa/drivers/dri/i965/brw_fs.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
>> @@ -1828,6 +1828,56 @@ fs_visitor::assign_urb_setup()
>>        urb_start + prog_data->num_varying_inputs * 2;
>>  }
>>
>> +void
>> +fs_visitor::assign_vs_urb_setup()
>> +{
>> +   brw_vs_prog_data *vs_prog_data = (brw_vs_prog_data *) prog_data;
>> +   int grf, count, slot, channel, attr;
>> +
>> +   assert(stage == MESA_SHADER_VERTEX);
>> +   count = _mesa_bitcount_64(vs_prog_data->inputs_read);
>> +   if (vs_prog_data->uses_vertexid || vs_prog_data->uses_instanceid)
>> +      count++;
>> +
>> +   /* Each attribute is 4 regs. */
>> +   this->first_non_payload_grf =
>> +      payload.num_regs + prog_data->curb_read_length + count * 4;
>> +
>> +   unsigned vue_entries =
>> +      MAX2(count, vs_prog_data->base.vue_map.num_slots);
>> +
>> +   vs_prog_data->base.urb_entry_size = ALIGN(vue_entries, 4) / 4;
>> +   vs_prog_data->base.urb_read_length = (count + 1) / 2;
>> +
>> +   assert(vs_prog_data->base.urb_read_length <= 15);
>> +
>> +   /* Rewrite all ATTR file references to the hw grf that they land in. */
>> +   foreach_block_and_inst(block, fs_inst, inst, cfg) {
>> +      for (int i = 0; i < inst->sources; i++) {
>> +         if (inst->src[i].file == ATTR) {
>> +
>> +            if (inst->src[i].reg == VERT_ATTRIB_MAX) {
>> +               slot = count - 1;
>> +            } else {
>> +               attr = inst->src[i].reg + inst->src[i].reg_offset / 4;
>> +               slot = _mesa_bitcount_64(vs_prog_data->inputs_read &
>> +                                        BITFIELD64_MASK(attr));
>> +            }
>> +
>> +            channel = inst->src[i].reg_offset & 3;
>> +
>> +            grf = payload.num_regs +
>> +               prog_data->curb_read_length +
>> +               slot * 4 + channel;
>> +
>> +            inst->src[i].file = HW_REG;
>> +            inst->src[i].fixed_hw_reg =
>> +               retype(brw_vec8_grf(grf, 0), inst->src[i].type);
>> +         }
>> +      }
>> +   }
>> +}
>> +
>>  /**
>>   * Split large virtual GRFs into separate components if we can.
>>   *
>> @@ -3405,6 +3455,13 @@ fs_visitor::setup_payload_gen6()
>>  }
>>
>>  void
>> +fs_visitor::setup_vs_payload()
>> +{
>> +   /* R0: thread header, R1: urb handles */
>> +   payload.num_regs = 2;
>> +}
>> +
>> +void
>>  fs_visitor::assign_binding_table_offsets()
>>  {
>>     assert(stage == MESA_SHADER_FRAGMENT);
>> @@ -3471,6 +3528,8 @@ fs_visitor::opt_drop_redundant_mov_to_flags()
>>  void
>>  fs_visitor::optimize()
>>  {
>> +   const char *stage_name = stage == MESA_SHADER_VERTEX ? "vs" : "fs";
>> +
>>     calculate_cfg();
>>
>>     split_virtual_grfs();
>> @@ -3487,8 +3546,8 @@ fs_visitor::optimize()
>>                                                                          \
>>        if (unlikely(INTEL_DEBUG & DEBUG_OPTIMIZER) && this_progress) {   \
>>           char filename[64];                                             \
>> -         snprintf(filename, 64, "fs%d-%04d-%02d-%02d-" #pass,           \
>> -                  dispatch_width, shader_prog ? shader_prog->Name : 0, iteration, pass_num); \
>> +         snprintf(filename, 64, "%s%d-%04d-%02d-%02d-" #pass,              \
>> +                  stage_name, dispatch_width, shader_prog ? shader_prog->Name : 0, iteration, pass_num); \
>>                                                                          \
>>           backend_visitor::dump_instructions(filename);                  \
>>        }                                                                 \
>> @@ -3498,8 +3557,8 @@ fs_visitor::optimize()
>>
>>     if (unlikely(INTEL_DEBUG & DEBUG_OPTIMIZER)) {
>>        char filename[64];
>> -      snprintf(filename, 64, "fs%d-%04d-00-start",
>> -               dispatch_width, shader_prog ? shader_prog->Name : 0);
>> +      snprintf(filename, 64, "%s%d-%04d-00-start",
>> +               stage_name, dispatch_width, shader_prog ? shader_prog->Name : 0);
>>
>>        backend_visitor::dump_instructions(filename);
>>     }
>> @@ -3608,6 +3667,40 @@ fs_visitor::allocate_registers()
>>  }
>>
>>  bool
>> +fs_visitor::run_vs()
>> +{
>> +   assert(stage == MESA_SHADER_VERTEX);
>> +
>> +   assign_common_binding_table_offsets(0);
>> +   setup_vs_payload();
>> +
>> +   if (INTEL_DEBUG & DEBUG_SHADER_TIME)
>> +      emit_shader_time_begin();
>> +
>> +   foreach_in_list(ir_instruction, ir, shader->base.ir) {
>> +      base_ir = ir;
>> +      this->result = reg_undef;
>> +      ir->accept(this);
>> +   }
>> +   base_ir = NULL;
>> +   if (failed)
>> +      return false;
>> +
>> +   emit(FS_OPCODE_PLACEHOLDER_HALT);
>
> I don't think you want this.

I left it there because it's also an instruction scheduling barrier
between the main shader and the final writes.  I wasn't sure if we
needed that for some workaround, but as we discussed in IRC, it's
really only useful when we're actually discarding.

>> +
>> +   emit_urb_writes();
>> +
>> +   optimize();
>> +
>> +   assign_curb_setup();
>> +   assign_vs_urb_setup();
>> +
>> +   allocate_registers();
>> +
>> +   return !failed;
>> +}
>> +
>> +bool
>>  fs_visitor::run()
>>  {
>>     sanity_param_count = prog->Parameters->NumParameters;
>> diff --git a/src/mesa/drivers/dri/i965/brw_fs.h b/src/mesa/drivers/dri/i965/brw_fs.h
>> index 55d2a8d..1a44704 100644
>> --- a/src/mesa/drivers/dri/i965/brw_fs.h
>> +++ b/src/mesa/drivers/dri/i965/brw_fs.h
>> @@ -310,12 +310,23 @@ public:
>>                struct gl_shader_program *shader_prog,
>>                struct gl_fragment_program *fp,
>>                unsigned dispatch_width);
>> +
>> +   fs_visitor(struct brw_context *brw,
>> +              void *mem_ctx,
>> +              const struct brw_vs_prog_key *key,
>> +              struct brw_vs_prog_data *prog_data,
>> +              struct gl_shader_program *shader_prog,
>> +              struct gl_vertex_program *cp,
>> +              unsigned dispatch_width);
>> +
>>     ~fs_visitor();
>>     void init();
>>
>>     fs_reg *variable_storage(ir_variable *var);
>>     int virtual_grf_alloc(int size);
>>     void import_uniforms(fs_visitor *v);
>> +   void setup_uniform_clipplane_values();
>> +   void compute_clip_distance();
>>
>>     void visit(ir_variable *ir);
>>     void visit(ir_assignment *ir);
>> @@ -406,14 +417,17 @@ public:
>>                                          uint32_t const_offset);
>>
>>     bool run();
>> +   bool run_vs();
>>     void optimize();
>>     void allocate_registers();
>>     void assign_binding_table_offsets();
>>     void setup_payload_gen4();
>>     void setup_payload_gen6();
>> +   void setup_vs_payload();
>>     void assign_curb_setup();
>>     void calculate_urb_setup();
>>     void assign_urb_setup();
>> +   void assign_vs_urb_setup();
>>     bool assign_regs(bool allow_spilling);
>>     void assign_regs_trivial();
>>     void get_used_mrfs(bool *mrf_used);
>> @@ -471,6 +485,7 @@ public:
>>     fs_reg *emit_samplepos_setup();
>>     fs_reg *emit_sampleid_setup();
>>     fs_reg *emit_general_interpolation(ir_variable *ir);
>> +   fs_reg *emit_vs_system_value(enum brw_reg_type type, int location);
>>     void emit_interpolation_setup_gen4();
>>     void emit_interpolation_setup_gen6();
>>     void compute_sample_position(fs_reg dst, fs_reg int_sample_pos);
>> @@ -557,6 +572,7 @@ public:
>>     fs_inst *emit_single_fb_write(fs_reg color1, fs_reg color2,
>>                                   fs_reg src0_alpha, unsigned components);
>>     void emit_fb_writes();
>> +   void emit_urb_writes();
>>
>>     void emit_shader_time_begin();
>>     void emit_shader_time_end();
>> @@ -632,8 +648,8 @@ public:
>>     struct hash_table *variable_ht;
>>     fs_reg frag_depth;
>>     fs_reg sample_mask;
>> -   fs_reg outputs[BRW_MAX_DRAW_BUFFERS];
>> -   unsigned output_components[BRW_MAX_DRAW_BUFFERS];
>> +   fs_reg outputs[VARYING_SLOT_MAX];
>> +   unsigned output_components[VARYING_SLOT_MAX];
>>     fs_reg dual_src_output;
>>     bool do_dual_src;
>>     int first_non_payload_grf;
>> @@ -680,6 +696,7 @@ public:
>>     fs_reg delta_x[BRW_WM_BARYCENTRIC_INTERP_MODE_COUNT];
>>     fs_reg delta_y[BRW_WM_BARYCENTRIC_INTERP_MODE_COUNT];
>>     fs_reg shader_start_time;
>> +   fs_reg userplane[MAX_CLIP_PLANES];
>>
>>     int grf_used;
>>     bool spilled_any_registers;
>> diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>> index 264bd98..9f17e5d 100644
>> --- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>> +++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
>> @@ -43,11 +43,40 @@ extern "C" {
>>  #include "brw_eu.h"
>>  #include "brw_wm.h"
>>  }
>> +#include "brw_vec4.h"
>>  #include "brw_fs.h"
>>  #include "main/uniforms.h"
>>  #include "glsl/glsl_types.h"
>>  #include "glsl/ir_optimization.h"
>>
>> +fs_reg *
>> +fs_visitor::emit_vs_system_value(enum brw_reg_type type, int location)
>> +{
>> +   fs_reg *reg = new(this->mem_ctx)
>> +      fs_reg(ATTR, VERT_ATTRIB_MAX, type);
>> +   brw_vs_prog_data *vs_prog_data = (brw_vs_prog_data *) prog_data;
>> +
>> +   switch (location) {
>> +   case SYSTEM_VALUE_BASE_VERTEX:
>> +      reg->reg_offset = 0;
>> +      vs_prog_data->uses_vertexid = true;
>> +      break;
>> +   case SYSTEM_VALUE_VERTEX_ID:
>> +   case SYSTEM_VALUE_VERTEX_ID_ZERO_BASE:
>> +      reg->reg_offset = 2;
>> +      vs_prog_data->uses_vertexid = true;
>> +      break;
>> +   case SYSTEM_VALUE_INSTANCE_ID:
>> +      reg->reg_offset = 3;
>> +      vs_prog_data->uses_instanceid = true;
>> +      break;
>> +   default:
>> +      unreachable("not reached");
>> +   }
>> +
>> +   return reg;
>> +}
>> +
>>  void
>>  fs_visitor::visit(ir_variable *ir)
>>  {
>> @@ -57,7 +86,11 @@ fs_visitor::visit(ir_variable *ir)
>>        return;
>>
>>     if (ir->data.mode == ir_var_shader_in) {
>> -      if (!strcmp(ir->name, "gl_FragCoord")) {
>> +      if (stage == MESA_SHADER_VERTEX) {
>> +         reg = new(this->mem_ctx)
>> +            fs_reg(ATTR, ir->data.location,
>> +                   brw_type_for_base_type(ir->type->get_scalar_type()));
>> +      } else if (!strcmp(ir->name, "gl_FragCoord")) {
>>          reg = emit_fragcoord_interpolation(ir);
>>        } else if (!strcmp(ir->name, "gl_FrontFacing")) {
>>          reg = emit_frontfacing_interpolation();
>> @@ -70,7 +103,19 @@ fs_visitor::visit(ir_variable *ir)
>>     } else if (ir->data.mode == ir_var_shader_out) {
>>        reg = new(this->mem_ctx) fs_reg(this, ir->type);
>>
>> -      if (ir->data.index > 0) {
>> +      if (stage == MESA_SHADER_VERTEX) {
>> +        int vector_elements =
>> +           ir->type->is_array() ? ir->type->fields.array->vector_elements
>> +                                : ir->type->vector_elements;
>> +
>> +        for (int i = 0; i < (type_size(ir->type) + 3) / 4; i++) {
>> +           int output = ir->data.location + i;
>> +           this->outputs[output] = *reg;
>> +           this->outputs[output].reg_offset = i * 4;
>> +           this->output_components[output] = vector_elements;
>> +        }
>> +
>> +      } else if (ir->data.index > 0) {
>>          assert(ir->data.location == FRAG_RESULT_DATA0);
>>          assert(ir->data.index == 1);
>>          this->dual_src_output = *reg;
>> @@ -134,15 +179,26 @@ fs_visitor::visit(ir_variable *ir)
>>        reg->type = brw_type_for_base_type(ir->type);
>>
>>     } else if (ir->data.mode == ir_var_system_value) {
>> -      if (ir->data.location == SYSTEM_VALUE_SAMPLE_POS) {
>> +      switch (ir->data.location) {
>> +      case SYSTEM_VALUE_BASE_VERTEX:
>> +      case SYSTEM_VALUE_VERTEX_ID:
>> +      case SYSTEM_VALUE_VERTEX_ID_ZERO_BASE:
>> +      case SYSTEM_VALUE_INSTANCE_ID:
>> +         reg = emit_vs_system_value(brw_type_for_base_type(ir->type),
>> +                                    ir->data.location);
>> +         break;
>> +      case SYSTEM_VALUE_SAMPLE_POS:
>>          reg = emit_samplepos_setup();
>> -      } else if (ir->data.location == SYSTEM_VALUE_SAMPLE_ID) {
>> +         break;
>> +      case SYSTEM_VALUE_SAMPLE_ID:
>>          reg = emit_sampleid_setup();
>> -      } else if (ir->data.location == SYSTEM_VALUE_SAMPLE_MASK_IN) {
>> +         break;
>> +      case SYSTEM_VALUE_SAMPLE_MASK_IN:
>>           assert(brw->gen >= 7);
>>           reg = new(mem_ctx)
>>              fs_reg(retype(brw_vec8_grf(payload.sample_mask_in_reg, 0),
>>                            BRW_REGISTER_TYPE_D));
>> +         break;
>>        }
>>     }
>>
>> @@ -1709,6 +1765,8 @@ get_tex(gl_shader_stage stage, const void *key)
>>     switch (stage) {
>>     case MESA_SHADER_FRAGMENT:
>>        return &((brw_wm_prog_key*) key)->tex;
>> +   case MESA_SHADER_VERTEX:
>> +      return &((brw_vec4_prog_key*) key)->tex;
>>     default:
>>        unreachable("unhandled shader stage");
>>     }
>> @@ -3394,6 +3452,231 @@ fs_visitor::emit_fb_writes()
>>  }
>>
>>  void
>> +fs_visitor::setup_uniform_clipplane_values()
>> +{
>> +   gl_clip_plane *clip_planes = brw_select_clip_planes(ctx);
>> +   const struct brw_vec4_prog_key *key =
>> +      (const struct brw_vec4_prog_key *) this->key;
>> +
>> +   for (int i = 0; i < key->nr_userclip_plane_consts; i++) {
>> +      this->userplane[i] = fs_reg(UNIFORM, uniforms);
>> +      for (int j = 0; j < 4; ++j) {
>> +         stage_prog_data->param[uniforms + j] =
>> +            (gl_constant_value *) &clip_planes[i][j];
>> +      }
>> +      uniforms += 4;
>> +   }
>> +}
>> +
>> +void fs_visitor::compute_clip_distance()
>> +{
>> +   struct brw_vec4_prog_data *vec4_prog_data =
>> +      (struct brw_vec4_prog_data *) prog_data;
>> +   const struct brw_vec4_prog_key *key =
>> +      (const struct brw_vec4_prog_key *) this->key;
>> +
>> +   gl_varying_slot clip_vertex = VARYING_SLOT_CLIP_VERTEX;
>> +   if (!(vec4_prog_data->vue_map.slots_valid & VARYING_BIT_CLIP_VERTEX))
>> +      clip_vertex = VARYING_SLOT_POS;
>> +
>> +   /* If the clip vertex isn't written, skip this.  Typically this means
>> +    * the GS will set up clipping. */
>> +   if (outputs[clip_vertex].file == BAD_FILE)
>> +      return;
>> +
>> +   setup_uniform_clipplane_values();
>> +
>> +   current_annotation = "user clip distances";
>> +
>> +   this->outputs[VARYING_SLOT_CLIP_DIST0] = fs_reg(this, glsl_type::vec4_type);
>> +   this->outputs[VARYING_SLOT_CLIP_DIST1] = fs_reg(this, glsl_type::vec4_type);
>> +
>> +   for (int i = 0; i < key->nr_userclip_plane_consts; i++) {
>> +      fs_reg u = userplane[i];
>> +      fs_reg output = outputs[VARYING_SLOT_CLIP_DIST0 + i / 4];
>> +      output.reg_offset = i & 3;
>> +
>> +      emit(MUL(output, outputs[clip_vertex], u));
>> +      for (int j = 1; j < 4; j++) {
>> +         u.reg = userplane[i].reg + j;
>> +         emit(MAD(output, output, offset(outputs[clip_vertex], j), u));
>> +      }
>> +   }
>> +}
>> +
>> +void
>> +fs_visitor::emit_urb_writes()
>> +{
>> +   int mrf;
>> +   int slot, urb_offset;
>> +   struct brw_vec4_prog_data *vec4_prog_data =
>> +      (struct brw_vec4_prog_data *) prog_data;
>> +   const struct brw_vec4_prog_key *key =
>> +      (const struct brw_vec4_prog_key *) this->key;
>> +   const GLbitfield64 psiz_mask =
>> +      VARYING_BIT_LAYER | VARYING_BIT_VIEWPORT | VARYING_BIT_PSIZ;
>> +   bool flush;
>> +   fs_reg sources[8];
>> +
>> +   /* Lower legacy ff and ClipVertex clipping to clip distances */
>> +   if (key->userclip_active && !prog->UsesClipDistanceOut)
>> +      compute_clip_distance();
>> +
>> +   /* If we don't have any valid slots to write, just do a minimal urb write
>> +    * send to terminate the shader. */
>> +   if (vec4_prog_data->vue_map.slots_valid == 0) {
>> +
>> +      fs_reg *payload_sources = ralloc_array(mem_ctx, fs_reg, 1);
>> +      fs_reg payload = fs_reg(GRF, virtual_grf_alloc(1),
>> +                              BRW_REGISTER_TYPE_F);
>> +
>> +      fs_reg dummy = fs_reg(GRF, virtual_grf_alloc(1), BRW_REGISTER_TYPE_UD);
>> +      fs_inst *inst = emit(MOV(dummy, fs_reg(retype(brw_vec8_grf(1, 0),
>> +                                                    BRW_REGISTER_TYPE_UD))));
>> +      inst->force_writemask_all = true;
>> +
>> +      payload_sources[0] = dummy;
>> +
>> +      emit(LOAD_PAYLOAD(payload, payload_sources, 1));
>
> A one source load_payload?

Oh hehe, I guess that's not necessary...

>> +
>> +      inst = emit(VS_OPCODE_URB_WRITE, reg_undef, payload);
>> +      inst->eot = true;
>> +      inst->mlen = 1;
>> +      inst->offset = 1;
>> +      return;
>> +   }
>> +
>> +   mrf = 0;
>
> I probably wouldn't name this mrf, since Gen8+ doesn't have them. :)
>
> We use 'length' in the ir_texture visitor, and that would make reading
> some of the code later than uses mrf easier to read.

Yeah, I used mrfs when I started this work and converted to LOAD_PAYLOAD later.

>> +   urb_offset = 0;
>> +   flush = false;
>> +   for (slot = 0; slot < vec4_prog_data->vue_map.num_slots; slot++) {
>> +      fs_reg reg, src, zero;
>> +
>> +      int varying = vec4_prog_data->vue_map.slot_to_varying[slot];
>> +      switch (varying) {
>> +      case VARYING_SLOT_PSIZ:
>> +
>> +         /* The point size varying slot is the vue header and is always in the
>> +          * vue map.  But often none of the special varyings that live there
>> +          * are written and in that case we can skip writing to the vue
>> +          * header, provided the corresponding state properly clamps the
>> +          * values further down the pipeline. */
>> +         if ((vec4_prog_data->vue_map.slots_valid & psiz_mask) == 0) {
>> +            assert(mrf == 0);
>> +            urb_offset++;
>> +            break;
>> +         }
>> +
>> +         zero = fs_reg(GRF, virtual_grf_alloc(1), BRW_REGISTER_TYPE_UD);
>> +         emit(MOV(zero, fs_reg(0u)));
>> +
>> +         sources[mrf++] = zero;
>> +         if (vec4_prog_data->vue_map.slots_valid & VARYING_BIT_LAYER)
>> +            sources[mrf++] = this->outputs[VARYING_SLOT_LAYER];
>> +         else
>> +            sources[mrf++] = zero;
>> +
>> +         if (vec4_prog_data->vue_map.slots_valid & VARYING_BIT_VIEWPORT)
>> +            sources[mrf++] = this->outputs[VARYING_SLOT_VIEWPORT];
>> +         else
>> +            sources[mrf++] = zero;
>> +
>> +         if (vec4_prog_data->vue_map.slots_valid & VARYING_BIT_PSIZ)
>> +            sources[mrf++] = this->outputs[VARYING_SLOT_PSIZ];
>> +         else
>> +            sources[mrf++] = zero;
>> +         break;
>> +
>> +      case BRW_VARYING_SLOT_NDC:
>> +      case VARYING_SLOT_EDGE:
>> +         unreachable("unexpected scalar vs output");
>> +         break;
>> +
>> +      case BRW_VARYING_SLOT_PAD:
>> +         break;
>> +
>> +      default:
>> +         /* gl_Position is always in the vue map, but isn't always written by
>> +          * the shader.  Other varyings (clip distances) get added to the vue
>> +          * map but doesn't always get written.  In those cases, the
>> +          * corresponding this->output slot will be invalid we can skip the
>> +          * urb write for the varying.  If we've already queued up a vue slot
>> +          * for writing we flush a mlen 5 urb write, otherwise we just advance
>> +          * the urb_offset.
>> +          */
>> +         if (this->outputs[varying].file == BAD_FILE) {
>> +            if (mrf > 0)
>> +               flush = true;
>> +            else
>> +               urb_offset++;
>> +            break;
>> +         }
>> +
>> +         for (int i = 0; i < 4; i++) {
>> +            if ((varying == VARYING_SLOT_COL0 ||
>> +                 varying == VARYING_SLOT_COL1 ||
>> +                 varying == VARYING_SLOT_BFC0 ||
>> +                 varying == VARYING_SLOT_BFC1) &&
>> +                key->clamp_vertex_color) {
>> +               /* We need to clamp these guys, so do a saturating MOV into a
>> +                * temp register and use that for the payload.
>> +                */
>> +               reg = fs_reg(GRF, virtual_grf_alloc(1), BRW_REGISTER_TYPE_F);
>> +               reg.type = this->outputs[varying].type;
>> +               src = offset(this->outputs[varying], i);
>> +               fs_inst *inst = emit(MOV(reg, src));
>> +               inst->saturate = true;
>> +               sources[mrf++] = reg;
>> +            } else {
>> +               sources[mrf++] = offset(this->outputs[varying], i);
>> +            }
>> +         }
>> +         break;
>> +      }
>> +
>> +      current_annotation = "URB write";
>> +
>> +      /* If we've queued up 8 registers of payload (2 VUE slots), if this is
>> +       * the last slot or if we need to flush (see BAD_FILE varying case
>> +       * above), emit a URB write send now to flush out the data.
>> +       */
>> +      int last = slot == vec4_prog_data->vue_map.num_slots - 1;
>> +      if (mrf == 8 || last)
>> +         flush = true;
>> +      if (flush) {
>> +         if (last && (INTEL_DEBUG & DEBUG_SHADER_TIME))
>> +            emit_shader_time_end();
>> +
>> +         fs_reg *payload_sources = ralloc_array(mem_ctx, fs_reg, mrf + 1);
>> +         fs_reg payload = fs_reg(GRF, virtual_grf_alloc(mrf + 1),
>> +                                 BRW_REGISTER_TYPE_F);
>> +
>> +         /* We need WE_all on the MOV for the message header (the URB handles)
>> +          * so do a MOV to a dummy register and set force_writemask_all on the
>> +          * MOV.  LOAD_PAYLOAD will preserve that.
>> +          */
>> +         fs_reg dummy = fs_reg(GRF, virtual_grf_alloc(1),
>> +                               BRW_REGISTER_TYPE_UD);
>> +         fs_inst *inst = emit(MOV(dummy, fs_reg(retype(brw_vec8_grf(1, 0),
>> +                                                       BRW_REGISTER_TYPE_UD))));
>> +         inst->force_writemask_all = true;
>> +         payload_sources[0] = dummy;
>> +
>> +         memcpy(&payload_sources[1], sources, mrf * sizeof sources[0]);
>> +         emit(LOAD_PAYLOAD(payload, payload_sources, mrf + 1));
>> +
>> +         inst = emit(VS_OPCODE_URB_WRITE, reg_undef, payload);
>> +         inst->eot = last;
>> +         inst->mlen = mrf + 1;
>> +         inst->offset = urb_offset;
>> +         urb_offset = slot + 1;
>> +         mrf = 0;
>> +         flush = false;
>> +      }
>> +   }
>> +}
>> +
>> +void
>>  fs_visitor::resolve_ud_negate(fs_reg *reg)
>>  {
>>     if (reg->type != BRW_REGISTER_TYPE_UD ||
>> @@ -3437,6 +3720,25 @@ fs_visitor::fs_visitor(struct brw_context *brw,
>>     init();
>>  }
>>
>> +fs_visitor::fs_visitor(struct brw_context *brw,
>> +                       void *mem_ctx,
>> +                       const struct brw_vs_prog_key *key,
>> +                       struct brw_vs_prog_data *prog_data,
>> +                       struct gl_shader_program *shader_prog,
>> +                       struct gl_vertex_program *cp,
>> +                       unsigned dispatch_width)
>> +   : backend_visitor(brw, shader_prog, &cp->Base, &prog_data->base.base,
>> +                     MESA_SHADER_VERTEX),
>> +     reg_null_f(retype(brw_null_vec(dispatch_width), BRW_REGISTER_TYPE_F)),
>> +     reg_null_d(retype(brw_null_vec(dispatch_width), BRW_REGISTER_TYPE_D)),
>> +     reg_null_ud(retype(brw_null_vec(dispatch_width), BRW_REGISTER_TYPE_UD)),
>> +     key(key), prog_data(&prog_data->base.base),
>> +     dispatch_width(dispatch_width)
>> +{
>> +   this->mem_ctx = mem_ctx;
>
> I suppose if we're using the constructor list for everything else, we
> might as well use it for mem_ctx.

You can't do that, it's a field in the super class (backend_visitor).
You can only chain to the super class constructors or initialize
fields in you own class in the initializer list.

Kristian


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